1. Field of the Disclosure
The present invention relates to humidifiers having water reservoirs and wicks that are resistant to microorganism growth.
2. Description of Related Art
A typical humidifier has a reservoir of water over or through which a stream of forced air is driven so as to pick up water vapor. The humidified airstream is then discharged to the ambient atmosphere, thereby increasing the humidity. Many humidifiers incorporate one or more wicks, the lower ends of which are located in a reservoir of water, thereby moistening the wicks. The large surface area of the wicks promotes rapid evaporation of water as the air stream is blown over and through them.
A common problem of humidifiers is the growth of microorganisms, such as mold spores and bacteria, in the water reservoir and wick when the humidifier is shut off for an extended period of time. Airborne microorganisms are then free to multiply in the stagnant water and in the moist wicks so long as a food supply is available. For simple reservoirs, the food supply includes contaminants in the water, either originally present in the water supply or deposited over time from contaminants in the airstream. Fortunately, these contaminants are usually in minute concentrations. For humidifiers that utilize wicks, however, the problem is more acute because the wick material itself is usually a fibrous organic material (e.g., paper, cotton or other textile) that is itself food to many microorganisms.
Various schemes are known in the art for destroying existing microorganisms in humidifier water reservoirs, such as heat, biocides, and filters. Such solutions are either energy intensive, require expensive chemicals and regular maintenance, or require the cleaning or replacement of expensive microfilters. In some cases anti-microbial material may be incorporated within the wicks to reduce mold growth.
A simple and inexpensive solution is to blow dry the reservoir when not in use. In actual operation, however, a shallow layer of water typically remains. Further, even if the water level in the reservoir went to zero, the wick would still be wet when the humidifier shuts off. A similiar solution is disclosed in Stanek et al., U.S. Pat. No. 6,550,748 B2, entitled DRY OUT MECHANISM FOR HUMIDIFIER, issued Apr. 22, 2003, wherein the user may put the humidifier in a “dry out” mode wherein the fan keeps blowing regardless of the water level.
A problem with a “dry out” mode type of humidifier is apparent when one considers the situation where the reservoir is nearly completely full and the user now desires to shut the humidifier off. For a typical home humidifier with a reservoir capable of holding one or more gallons of water, it could take hours, if not days, to dry out the reservoir. This is quite an uncomfortable situation for the user who wants the device shut off. Further, the user has to check upon the water level from time to time to check to see that the water is evaporated and any wick is dried out, so that the user may shut the device off.
One solution to this problem is to provide a dual reservoir system that may have one portion that is completely full, and another portion that is substantially empty, so that only a small amount of residual water need be evaporated to dry out the reservoir and any wicks.